/* Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; version 2 of the License.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software Foundation,
   51 Franklin Street, Suite 500, Boston, MA 02110-1335 USA */

#ifndef TABLE_MAPPING_H
#define TABLE_MAPPING_H

/* Forward declarations */
#ifndef MYSQL_CLIENT
    struct TABLE;
#else
    class Table_map_log_event;
    typedef Table_map_log_event TABLE;
    void free_table_map_log_event(TABLE *table);
#endif


/*
  CLASS table_mapping

  RESPONSIBILITIES
    The table mapping is used to map table id's to table pointers

  COLLABORATION
    RELAY_LOG    For mapping table id:s to tables when receiving events.
 */

/*
  Guilhem to Mats:
  in the table_mapping class, the memory is allocated and never freed (until
  destruction). So this is a good candidate for allocating inside a MEM_ROOT:
  it gives the efficient allocation in chunks (like in expand()). So I have
  introduced a MEM_ROOT.

  Note that inheriting from Sql_alloc had no effect: it has effects only when
  "ptr= new table_mapping" is called, and this is never called. And it would
  then allocate from thd->mem_root which is a highly volatile object (reset
  from example after executing each query, see dispatch_command(), it has a
  free_root() at end); as the table_mapping object is supposed to live longer
  than a query, it was dangerous.
  A dedicated MEM_ROOT needs to be used, see below.
*/

#include "hash.h"                               /* HASH */

class table_mapping
{

private:
    MEM_ROOT m_mem_root;

public:

    enum enum_error
    {
        ERR_NO_ERROR = 0,
        ERR_LIMIT_EXCEEDED,
        ERR_MEMORY_ALLOCATION
    };

    table_mapping();
    ~table_mapping();

    TABLE *get_table(ulong table_id);

    int       set_table(ulong table_id, TABLE *table);
    int       remove_table(ulong table_id);
    void      clear_tables();
    ulong     count() const
    {
        return m_table_ids.records;
    }

private:
    /*
      This is a POD (Plain Old Data).  Keep it that way (we apply offsetof() to
      it, which only works for PODs)
    */
    struct entry
    {
        ulong table_id;
        union {
            TABLE *table;
            entry *next;
        };
    };

    entry *find_entry(ulong table_id)
    {
        return (entry *) my_hash_search(&m_table_ids,
                                        (uchar *)&table_id,
                                        sizeof(table_id));
    }
    int expand();

    /*
      Head of the list of free entries; "free" in the sense that it's an
      allocated entry free for use, NOT in the sense that it's freed
      memory.
    */
    entry *m_free;

    /* Correspondance between an id (a number) and a TABLE object */
    HASH m_table_ids;
};

#endif
